Hmmm this could be a bit left field, (and I'm assuming it's the bakelite/phenolic that is the magic ingredient in Garolite LE), but I wonder how similar phenolic used for some PCB blank's is to Garolite LE?
I'd be curious to get hold of some 1/32 or even 1/64 single sided phenolic substrate PCB blank and print on the non copper side.
I suggest thinner stock for better fixing to a piece of glass underneath or similar, as PCB blanks aren't always the flattest.
Just a random thought but might be worth a crack, search for 'phenolic pcb'
And I'd be very curious to hear how it goes.